Canisters used for containing a desiccant media designed to absorb moisture use a flexible bag made of an air permeable polyester mesh material to contain the media. The bag is difficult to manufacture in that the process begins with a piece of rectangular polyester mesh material which a seamstress sews two opposed sides of the rectangular piece together. This creates an open ended flexible cylinder. A circular piece of a mesh material is then sewn to one end of the flexible cylinder to provide a bottom for the cylinder. A second circular piece of mesh material is sewn part way to the upper end of the cylinder. The part way sewing provides an upper seam having a distance of about 3/4 of the circumference of the cylinder. This leaves a 1/4 "open" container, which is then filled with a desiccant particulate media and weighed. The incompleted upper seam of the open end is then completed by hand stitching to close the cylinder.
The mesh bag is flexible and manipulative thereby making it hard to handle during the sewing and filling process. The bags are, thus, not filled consistently because of the bag instability and the above complexity of the manufacturing process. This, in turn, has led to varying bag sizes as manufacturers endeavor to find a bag size that will provide the correct amount of desiccant media for the customer. The result has been a variety of bag sizes resulting in differing product performance in the process of absorbing moisture. The above weighing step does not ensure a proper amount of desiccant. Desiccant pellets vary in size & density. A "full" bag has varied from three to four plus pounds. Also, in shipment, the desiccant settles so that a "full" bag at the start of the manufacturing process, in many instances, does not remain full.
For shipping and ease of installation, the mesh bag is inserted into a metal cylinder and the combination placed in a plastic bag.
When the customer receives the metal cylinder containing the mesh bag and desiccant media, the metal cylinder is removed from the plastic bag and placed atop a dryer cavity and the plastic bag discarded. Using a minimal force against the bag, the bag is manually inserted into the cavity from the cylinder. With the bag located in the dryer cavity, the metal shipping container is removed from atop the cavity and discarded.
For those field personnel experienced in installing the flexible bag, the above process is rather straightforward but the discard of the plastic bag and metal cylinder is wasteful.